The present invention relates in general to downhole electrical connectors for use in oil field applications, and in particular to a downhole pothead seal for connecting a motor lead to an electrical motor of a submersible pump assembly using pressure energized lip seals.
Electric submersible pumps have been used in oil wells to pump well fluids for many years. These types of prior art submersible pumps include electrical connectors for connecting the electric motors of the pumps to electrical conductors of downhole cables. These pumps are often used in corrosive environments such as wells that produce sour gas, and hydrogen sulfide (H2S). Electrical connectors for electric submersible pumps typically have elastomeric seals or pothead connectors.
A problem encountered with pothead connections is the movement of conductors within the connector during installation and/or handling. This movement can cause shear stress damage to the cable insulation and the insulation within the connector itself, either of which is likely lead to the failure of the electrical connection.
As is particularly well known in the oil industry, the maintenance of power to such a pump is critical and at the same time made difficult by reasons of the extreme in pressures and temperatures and the character and nature of the well fluids to which the portion of the electric feedthrough system at the pump motor is subjected. That many problems have resulted from such circumstances has been frequently exhibited in the prior art apparatus applied for the same purpose. These problems have stemmed from many factors, not the least of which has been design characteristics of prior art apparatus which in many cases include the requirement for complete bonding of insulators and dielectrics thereof to one another and to the conductors which they peripherally encase as well as to the shell or housing by which they themselves are encased. Such a requirement is most difficult to satisfy. Where the bonding is not perfect, the pressure and temperature conditions within a well will make the electric feedthrough apparatus subject to infiltration by and seepage therein of well fluids with many undesirable results: short circuiting of the pump or motor, and electrical arcing or fire.
The improvements of the present invention substantially obviate many of the aforementioned problems. The inventor is not aware of any prior art which is specially pertinent to the improvements of the present invention as herein set forth and specifically claimed.
A pothead connector for use with an electric submersible pump is provided to connect a downhole cable to an electrical motor of the submersible pump. The pothead connector has a housing having a rearward or upper end and a forward or lower end. The downhole cable has electrical conductors that are separately covered by insulation layers. The downhole cable extends through the upper end and into the housing, and then is electrically connected to the electric motor through the lower end of the housing.
Two insulating blocks are provided in the lower end of the housing for separating and holding the electrical conductors in alignment and to prevent lateral movement of the conductors within the housing. A bore is provided through both the insulating blocks for each of the conductors. Each bore is provided with annular shoulders that face each other, one in the upper block and one in the lower block, for supporting and enclosing a seal that is located between the two blocks within the housing. The sealing ring has inner and outer lips some of which face the upper end of the housing, and the remainder of which face the lower end of the housing.
The inner lips of the seal provide a seal against the electrical conductors, and the outer lip of the seal provides a seal against the housing in the embodiment shown. The seal has a central web where all of the inner lips are connected to the outer lip. The seal also has openings for receiving each electrical conductor to feed them to a downhole pump motor.